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Capillary‐channeled polymer (C‐CP) fibers are demonstrated as a selective stationary phase for phosphopeptide analysis via LC–MS. Taking advantage of the oxidative self‐polymerization of dopamine under alkaline conditions, a simple system involving a dilute aqueous solution of 0.2% w/v dopamine hydrochloride in 0.15% w/v TRIS buffer, pH 8.5 was utilized to coat polydopamine onto nylon 6 C‐CP fibers. Confirmation of the polydopamine coating on the fibers (nylon‐PDA) was made through attenuated total reflection‐FTIR (ATR‐FTIR) analysis. Imaging using SEM was also performed to examine the morphology and topography of the nylon‐PDA. Subsequent loading of Fe³⁺to the nylon‐PDA matrix was confirmed by SEM/energy dispersive X‐ray spectroscopy (SEM/EDX). The Fe³⁺‐bound nylon‐PDA fibers packed in a microbore column format were tested in the off‐line preconcentration of phosphopeptides from a 1:100 mixture of β‐casein/BSA digests for MALDI‐TOF analysis. The packed column was also installed onto an HPLC system as a platform for the online sample clean‐up and enrichment of phosphopeptides from a 1:1000 mixture of β‐casein/BSA protein digests that were determined by subsequent ESI–MS analysis.